Control valve for variable displacement compressor

ABSTRACT

A control valve is configured such that as a position of a high pressure-side valve body positioned by a solenoid is closer to one side, a degree of opening for communication of a high pressure valve portion is more widened and a pressure on the side of a discharge flow path acting on the high pressure-side valve body is weakened. Further, the control valve is configured such that as a position of a low pressure-side valve body positioned by the solenoid is closer to the other side, a degree of opening for communication of a low pressure valve portion is more widened. When the high pressure-side valve body and the low pressure-side valve body are integrally positioned on the one side by the solenoid and the low pressure-side valve body is positioned on the other side by the solenoid, the high pressure-side valve body and the low pressure-side valve body are separated from each other.

TECHNICAL FIELD

The present invention relates to a control valve for a variabledisplacement compressor.

BACKGROUND ART

As a conventional control valve for a variable displacement compressorused for a refrigeration cycle of an automotive air conditioning system,there has been known a control valve including a high pressure valveportion provided in an introducing-side communication passage whichbrings a discharge flow path and a control pressure chamber of thevariable displacement compressor into communication with each other, anda low pressure valve portion provided in a discharging-sidecommunication passage which brings an intake flow path and the controlpressure chamber, in which a degree of opening for communication betweenthe high pressure valve portion and the low pressure valve portion isvariably controlled, thereby changing a pressure in the control pressurechamber to change an angle of a swash plate.

According to such a configuration, a case chamber (crank chamber) isused as the control pressure chamber in many cases. In such a case, if acontrol pressure (pressure in the control pressure chamber) isincreased, the angle of the swash plate is reduced and the dischargecapacity is reduced, and if the control pressure is reduced, the angleof the swash plate is increased and the discharge capacity is increased(patent document 1, for example).

In the control valve disclosed in the patent document 1, however, in aball valve as the high pressure valve portion, a discharge pressure isapplied in a direction closing a valve body. Therefore, when control isperformed to reduce the angle of the swash plate to reduce the dischargecapacity, there is concern that the high pressure valve portion isclosed unintentionally by the discharge pressure, the control pressureis reduced, the angle of the swash plate is increased and the dischargecapacity is increased.

In addition to the high pressure valve portion having the ball valve,there is also a conventional high pressure valve portion in which avalve body of the low pressure valve portion is integrally formed on aspool valve as the high pressure valve portion. In such a case, there isa problem that since a pressure leaks from a clearance generated betweena sleeve and a spool in the high pressure valve portion, the actuationof the air conditioning system delays when the cooling operation isstarted.

Therefore, it is an object of the present invention to obtain a controlvalve for a variable displacement compressor capable of preventing ahigh pressure valve portion from being unintentionally closed byincrease of a discharge pressure, capable of preventing an angle of aswash plate from increasing, and capable of enhancing the actuatingperformance. Patent document 1: International Publication WO2004/065789

DISCLOSURE OF INVENTION

According to the present invention, a control valve for a variabledisplacement compressor comprises a high pressure valve portion providedin an introducing-side communication passage which brings a dischargeflow path and a control pressure chamber of the variable displacementcompressor into communication with each other, and a low pressure valveportion provided in a discharging-side communication passage whichbrings an intake flow path and the control pressure chamber intocommunication with each other, in which degree of opening forcommunication of the high pressure valve portion and the low pressurevalve portion are variably controlled, thereby varying a pressure in thecontrol pressure chamber to change an angle of a swash plate, whereinthe control valve further comprises a position control unit whichcontrols advancing/retracting positions of a high pressure-side valvebody of the high pressure valve portion and a low pressure-side valvebody of the low pressure valve portion, as a position of the highpressure-side valve body positioned by the position control unit iscloser to one side, a degree of opening for communication of the highpressure valve portion is more widened, a pressure on the side of adischarge flow path acting on the high pressure-side valve body isweakened, as a position of the low pressure-side valve body positionedby the position control unit is closer to the other side, a degree ofopening for communication of the low pressure valve portion is morewidened, and when the high pressure-side valve body and the lowpressure-side valve body are integrally positioned on the one side bythe position control unit and the low pressure-side valve body ispositioned on the other side by the position control unit, the highpressure-side valve body and the low pressure-side valve body areseparated from each other.

According to the present invention, when the high pressure-side valvebody and the low pressure-side valve body are positioned on the one sideby the position control unit, the low pressure valve portion is fullyclosed.

According to the present invention, there is provided an urging unitwhich urges, of the high pressure-side valve body and the lowpressure-side valve body, only the low pressure-side valve body towardthe other side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of apparatus configurations of a variabledisplacement compressor and a control valve according to an embodimentof the present invention.

FIG. 2 is a vertical sectional view of the control valve for thevariable displacement compressor according to the embodiment of thepresent invention, and shows that a high pressure valve portion isclosed and a low pressure valve portion is opened.

FIG. 3 is an enlarged view of a portion A in FIG. 2.

FIG. 4 is an enlarged view of a portion B in FIG. 2.

FIG. 5 is a vertical sectional view of the control valve for thevariable displacement compressor according to the embodiment of thepresent invention, and shows that the high pressure valve portion isopened and the low pressure valve portion is closed.

FIG. 6 is a graph showing a correlation between a position of a movableportion of the control valve for the variable displacement compressorand opening areas of the high pressure valve portion and the lowpressure valve portion according to the embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be explained below in detailwith reference to the accompanying drawings. FIG. 1 is a schematicdiagram of apparatus configurations of a variable displacementcompressor and a control valve according to the embodiment, FIG. 2 is avertical sectional view of the control valve, and shows that a highpressure valve portion is closed and a low pressure valve portion isopened, FIG. 3 is an enlarged view of a portion A in FIG. 2, FIG. 4 isan enlarged view of a portion B in FIG. 2, FIG. 5 is a verticalsectional view of the control valve, and shows that the high pressurevalve portion is opened and the low pressure valve portion is closed,and FIG. 6 is a graph showing a correlation between a position of amovable portion of the control valve and opening areas of the highpressure valve portion and the low pressure valve portion.

As shown in FIG. 1, a control valve 1 according to the presentembodiment controls a control pressure Pc which changes an inclinationangle of a swash plate 2 a to change a discharge capacity of a variabledisplacement compressor 2, and the control valve 1 controls a pressure(control pressure) Pc in a case chamber 3 as a control pressure chamberfor example. In this case, the lower the pressure Pc in the case chamber3 is, the greater a pressure difference applied to a piston in thevariable displacement compressor 2 becomes and the discharge capacity isincreased. On the contrary, the higher the pressure in the case chamber3 is, the lower the discharge capacity becomes.

The control pressure Pc is produced as an intermediate pressure betweena pressure of refrigerant (discharge pressure) Pd in a discharge flowpath 4 (e.g., discharge port) and a pressure of refrigerant (intakepressure) Ps in an intake flow path 5 (e.g., intake port). For thispurpose, the control valve 1 includes a high pressure valve portion 7and a low pressure valve portion 9. The high pressure valve portion 7 isprovided in an introducing-side communication passage 6 which brings thedischarge flow path 4 and the case chamber 3 into communication witheach other. The high pressure valve portion 7 variably controls a degreeof opening for communication of the introducing-side communicationpassage 6. The low pressure valve portion 9 is provided in adischarging-side communication passage 8 which brings the intake flowpath 5 and the case chamber 3 into communication with each other. Thelow pressure valve portion 9 variably controls a degree of opening forcommunication of the discharging-side communication passage 8. Byadjusting these degrees of opening for communication, the controlpressure Pc is produced. In the case of such a configuration, as thedegree of opening for communication of the high pressure valve portion 7is larger, the control pressure Pc becomes closer to the dischargepressure Pd and becomes higher, and as the degree of opening forcommunication of the low pressure valve portion 9 is larger, the controlpressure Pc becomes closer to the intake pressure Ps and becomes lower.By controlling the degree of opening for communication of the highpressure valve portion 7 and the degree of opening for communication ofthe low pressure valve portion 9, it is possible to produce the controlpressure Pc while suppressing the refrigerant from flowing out from thedischarge flow path 4 toward the intake flow path 5 and while reducingthe energy loss.

In the present embodiment, the flow path (including the introducing-sidecommunication passage 6 and the discharging-side communication passage8) of refrigerant used for producing the control pressure Pc is alsoused as a refrigerant circulating path in the case chamber 3, and theflow path is used for lubricating and cooling a sliding portion. Forthis reason, an opening 6 a of the introducing-side communicationpassage 6 facing the case chamber 3 and an opening 8 a of thedischarging-side communication passage 8 facing the case chamber 3 areappropriately separated from each other, and a refrigerant pathextending from the high pressure valve portion 7 to the low pressurevalve portion 9 is long for some distance. Therefore, a pressure Pa inthe high pressure valve portion 7 on the side of the case chamber 3 isslightly higher than a pressure Pc2 in the low pressure valve portion 9on the side of the case chamber 3.

As shown in FIG. 2, the control valve 1 includes a solenoid 10 in whicha solenoid as a position control unit is incorporated, and a valveportion 11 in which the high pressure valve portion 7 and the lowpressure valve portion 9 are incorporated.

In the valve portion 11, a valve body (high pressure-side valve body 7a) of the high pressure valve portion 7 and a valve body (lowpressure-side valve body 9 a) of the low pressure valve portion 9 arepositioned and abutted against each other in tandem in anadvancing/retracting direction of a movable portion 10 a of thesolenoid, and the valve bodies are pushed against the movable portion 10a by coil springs 14 and 16 as an urging unit. By making theadvancing/retracting position of the movable portion 10 a variable,positions of the high pressure-side valve body 7 a and the lowpressure-side valve body 9 a are made variable, and the degree ofopening for communication of the high pressure valve portion 7 and thelow pressure valve portion 9 can be controlled. In the presentembodiment, the low pressure-side valve body 9 a is positioned on theside closer to the movable portion 10 a, and the high pressure-sidevalve body 7 a is positioned on the side further from the movableportion 10 a. In the following description, the direction of the arrow Xin FIGS. 2 to 5 is called a leading end side, and the opposite directionis called a base end side for convenience sake. The movable portion 10a, the low pressure-side valve body 9 a and the high pressure-side valvebody 7 a advance and retract along the X direction. The X directionextends along axial directions of a sleeve 12, a spool 13 and themovable portion 10 a of the solenoid.

The valve portion 11 includes a substantially cylindrical sleeve 12formed with a through hole 12 a in its longitudinal direction. Thethrough hole 12 a has a circular cross section. The spool 13 is insertedinto the through hole 12 a with an appropriate clearance, and the spool13 can advance and retract in the through hole 12 a along itslongitudinal direction.

The high pressure valve portion 7 is formed on the leading end side ofthe valve portion 11. A concrete configuration of the high pressurevalve portion 7 will be explained with reference to FIGS. 2 and 3.

A bottomed cylindrical recess 12 b is formed on the leading end side ofthe through hole 12 a of the sleeve 12. The recess 12 b has a diametergreater than that of the through hole 12 a. A side of an opening 12 e ofthe recess 12 b is closed with a lid 12 d.

An umbrella-like poppet 13 a is formed on a leading end of the spool 13.The poppet 13 a projects slightly radially outward of the through hole12 a. The poppet 13 a is accommodated in the recess 12 b. In a stateshown in FIGS. 2 and 3, a bottom surface 13 b of the poppet 13 a and abottom surface 12 c of the recess 12 b are abutted against each other.In the present embodiment, the poppet 13 a corresponds to the highpressure-side valve body 7 a of the high pressure valve portion 7, andthe bottom surface 12 c of the recess 12 b corresponds to its sealingsurface (sitting surface).

The coil spring 14 as an urging unit is interposed between the lid 12 dand the poppet 13 a. The poppet 13 a is urged toward the base end sidein the X direction, in the closing direction of the high pressure-sidevalve body 7 a by the coil spring 14.

A lateral hole port 12 f intersecting with the through hole 12 a isformed in the sleeve 12 at a location separating away from the opening12 e on the leading end side of the through hole 12 a toward the baseend side in the X direction by a predetermined distance. Adiameter-reduced portion 13 c which is narrowed is formed in the spool13 from the bottom surface 13 b of the poppet 13 a to a location opposedto the lateral hole port 12 f. The diameter-reduced portion 13 c has asubstantially constant circular cross section.

A side of the introducing-side communication passage 6 on the side ofthe case chamber 3 which is not shown in FIGS. 2 or 3 is incommunication with the recess 12 b through a through hole 12 g formed inthe lid 12 d, and a side of the introducing-side communication passage 6on the side of the discharge flow path 4 is in communication with thelateral hole port 12 f. A pressure in the recess 12 b, i.e., a backpressure of the poppet 13 a becomes a control pressure (Pa), and apressure in a gap 12 h corresponding to the lateral hole port 12 f andthe diameter-reduced portion 13 c of the spool 13 becomes the dischargepressure Pd.

The discharge pressure Pd is applied to an end surface of thediameter-reduced portion 13 c of the spool 13 on the side of the leadingend in the X direction toward the leading end side of the X direction,and the discharge pressure Pd is applied to an end surface of thediameter-reduced portion 13 c of the spool 13 on the side of the baseend in the X direction toward the leading end side in the X direction.Therefore, the discharge pressure Pd applied to the spool 13 is weakened(offset) in the axial direction of the spool 13.

In the configuration described above, if the spool 13 moves toward theleading end side in the X direction and the poppet 13 a as the highpressure-side valve body 7 a is separated away from the bottom surface12 c as the sitting surface, the high pressure valve portion 7 is openedand the introducing-side communication passage 6 is brought intocommunication. The degree of opening for communication of the highpressure valve portion 7 becomes larger in accordance with a distance ofthe poppet 13 a separated away from the bottom surface 12 c. A statewhere the spool 13 is located at the nearest position of the base endside in the X direction and the poppet 13 a sits on the bottom surface12 c corresponds to a state where the high pressure valve portion 7closes. In this state, the introducing-side communication passage 6 isshut. According to this configuration, the poppet 13 a is pushed againstthe bottom surface 12 c such that the poppet 13 a conforms to the bottomsurface 12 c, thereby enhancing the sealing performance of the highpressure valve portion 7. The position of the poppet 13 a in the Xdirection, i.e., the degree of opening for communication of the highpressure valve portion 7 is controlled by a solenoid as alater-described position control unit.

The low pressure valve portion 9 is formed on the valve portion 11 onthe side of the base end. A concrete configuration of the low pressurevalve portion 9 will be explained with reference to FIGS. 2, 4, and 5.

Another lateral hole port 12 i intersecting with the through hole 12 ais formed in the sleeve 12 at a location separating away from thelateral hole port 12 f by a predetermined distance toward the base endside in the X direction. A diameter-reduced portion 13 d which isnarrowed from a location opposed to the lateral hole port 12 i to an endon the base end side is formed on the spool 13. The diameter-reducedportion 13 d has a substantially constant circular cross section.

A clearance between the through hole 12 a and a section of the spool 13(general portion 13 e) existing between the lateral hole port 12 f andthe lateral hole port 12 i is narrowed so that leakage of refrigerantbetween the lateral hole ports 12 f and 12 i is reduced.

A bottomed cylindrical recess 12 j is formed in the sleeve 12 on thebase end side from the through hole 12 a. The recess 12 j has a diametergreater than that of the through hole 12 a. A leading end of a sidewall12 k of the recess 12 j is press-fitted into a recess groove 10 b formedin the leading end of the solenoid 10. With this configuration, thevalve portion 11 and the solenoid 10 are coupled to each other.

A poppet 15 as the low pressure-side valve body 9 a is positioned in therecess 12 j. A substantially cylindrical recess 15 a is formed in thepoppet 15. The diameter-reduced portion 13 d of the spool 13 is looselyinserted into the recess 15 a.

An annular projection 15 b is provided on the poppet 15 on the leadingend side in the X direction. As shown in FIG. 5, in a state where thepoppet 15 is located at the furthest position of the leading end side inthe X direction, the projection 15 b is inserted into the through hole12 a from its opening 12 m on the base end side of the through hole 12a, and a top surface 15 c around the projection 15 b and a bottomsurface 12 n of the recess 12 j abut against each other. As describedabove, in the present embodiment, the poppet 15 corresponds to the lowpressure-side valve body 9 a of the low pressure valve portion 9, andthe bottom surface 12 n of the recess 12 j corresponds to its sealingsurface (sitting surface).

A coil spring 16 as an urging unit is interposed between the bottomsurface 12 n and the poppet 15. The poppet 15 is urged toward the baseend side in the X direction, in the opening direction of the lowpressure-side valve body 9 a by the coil spring 16.

A side of the discharging-side communication passage 8 (not shown inFIGS. 2, 4, and 5) closer to the case chamber 3 is in communication withthe lateral hole port 12 i, and a side of the discharging-sidecommunication passage 8 closer to the intake flow path 5 is incommunication with the recess 12 j through a through hole 12 o formed inthe sidewall 12 k. With this configuration, a pressure in the recess 12j, i.e., a back pressure of the poppet 15 is the intake pressure Ps, anda pressure in the lateral hole port 12 i is the control pressure (Pc2).

That is, in the present embodiment, if the spool 13 moves toward thebase end side in the X direction and the poppet 15 as the lowpressure-side valve body 9 a separates from the bottom surface 12 n asthe sitting surface, the low pressure valve portion 9 opens and thedischarging-side communication passage 8 is brought into communication.The degree of opening for communication of the low pressure valveportion 9 becomes larger in accordance with a distance of the poppet 15separated away from the bottom surface 12 n. A state where the spool 13is located at the furthest position of the leading end side in the Xdirection and the poppet 15 sits on the bottom surface 12 n correspondsto a state where the low pressure valve portion 9 is closed. In thisstate, the discharging-side communication passage 8 is blocked.

According to this configuration, the poppet 15 is pushed against thebottom surface 12 n such that the poppet 15 conforms to the bottomsurface 12 n, thereby enhancing the sealing performance of the lowpressure valve portion 9. The position of the poppet 15 in the Xdirection, i.e., the degree of opening for communication of the lowpressure valve portion 9 is controlled by a solenoid as alater-described position control unit.

The movable portion 10 a of the solenoid 10 is positioned on the baseend side of the poppet 15 as the low pressure-side valve body 9 a.

In the present embodiment, the movable portion 10 a has such a shapethat a first member 10 c located on the leading end side in the Xdirection and a second member 10 d located on the base end side arearranged in the X direction and are integrally coupled to each other. Arecess 10 e is formed in the first member 10 c. A leading end side ofthe recess 10 e is widened in a conical shape and a base end of therecess 10 e is of a cylindrical shape. The poppet 15 is loosely insertedinto the recess 10 e. At that time, a bottom surface 15 d of the poppet15 abuts against a bottom surface 10 f of the recess 10 e, and thepoppet 15 is pushed against the first member 10 c by the coil spring 16.An axial deviation between the poppet 15 and the movable portion 10 acan be absorbed by a clearance between an inner wall of the recess 10 eand an outer wall of the poppet 15.

A flange 10 g is formed on a leading end of the first member 10 c. Theflange 10 g is latched together with an opening edge of a recess 10 iformed in leading end side of the casing 10 h of the solenoid 10,thereby limiting the movement of the movable portion 10 a toward thebase end side.

A coil spring 17 as an urging unit is interposed between a back surface10 j of the flange 10 g and a step 10 k formed on a sidewall of therecess 10 i. The movable portion 10 a is urged toward the leading endside in the X direction by the coil spring 17.

The recess 10 i is isolated by an annular plate-like diaphragm 18. Aperipheral edge of the diaphragm 18 is attached to the casing 10 h in asealed manner, and a central portion of the diaphragm 18 is nippedbetween the first member 10 c and the second member 10 d in a sealedmanner.

The recess 10 i is in communication with the recess 12 j through apassage 10 m which penetrates front and back surfaces of the flange 10g. Therefore, a pressure in the recess 10 i, i.e., a pressure acting ona surface (front surface) of the diaphragm 18 on the side of the leadingend is the intake pressure Ps. A pressure acting on a surface (backsurface) of the diaphragm 18 on the side of the base end is theatmospheric pressure. Therefore, if the intake pressure Ps exceeds apredetermined value, the movable portion 10 a is moved toward the baseend side by a pressure difference acting on the diaphragm 18.

A shaft 19 is coupled to the movable portion 10 a. The shaft 19 is urgedtoward the leading end side by a coil spring 20 as an urging unitpositioned on the base end side.

In the above configuration, if a coil 21 is energized, a suction forceacting toward the base end side is applied to the movable portion 10 a(second member 10 d). By adjusting the suction force by controllingcurrent flowing to the coil 21, positions, in the X direction, of themovable portion 10 a, the poppet 15 as the low pressure-side valve body9 a which abuts against the movable portion 10 a, and the poppet 13 a asthe high pressure-side valve body 7 a provided on the spool 13 whichabuts against the poppet 15 are determined by balance between thesuction force and the urging forces of the coil springs 14, 16, 17, and20 as the urging unit.

If the movable portion 10 a is moved toward the base end side bycontrolling the current supplied to the coil 21 or by increasing theintake pressure Ps acting on the diaphragm 18, the poppet 15 as the lowpressure-side valve body 9 a is also moved toward the base end side inassociation with the movable portion 10 a by the spring force of thecoil spring 16 as the urging unit, and the poppet 13 a as the highpressure-side valve body 7 a provided on the spool 13 is also movedtoward the base end side in association with the movable portion 10 a bythe spring force of the coil spring 14 as the urging unit.

According to the present embodiment, however, since poppet 15 and thespool 13 provided with the poppet 13 a are not coupled to each other andthey can separate from each other, after the poppet 13 a as the highpressure-side valve body 7 a sits on the bottom surface 12 c as thesitting surface, the poppet 15 separates from the spool 13 as shown inFIG. 2, and the degree of opening for communication of only the lowpressure valve portion 9 becomes larger.

FIG. 6 shows the degree of opening for communications of the highpressure valve portion 7 and the low pressure valve portion 9 withrespect to the position, in the X direction, of the movable portion 10 ain the control valve 1 having the configuration described above. In FIG.6, the lateral axis shows a position of the movable portion 10 a in theX direction, the right side is the base end side, and the left side isthe leading side. The vertical axis shows the degree of opening forcommunication (an area of opening).

The degree of opening for communication of the high pressure valveportion 7 is linearly varied depending upon the position of the movableportion 10 a, i.e., the position of the poppet 13 a. That is, in a statewhere the movable portion 10 a is located at the furthest position ofthe leading end side (FIG. 5), the degree of opening for communicationof the high pressure valve portion 7 becomes the maximum, the degree ofopening for communication of the high pressure valve portion 7 islinearly reduced as the position of the movable portion 10 a is variedtoward the base end side. When the poppet 13 a as the high pressure-sidevalve body 7 a abuts against the bottom surface 12 c as the sittingsurface, the high pressure valve portion 7 closes and its degree ofopening for communication becomes 0. If the high pressure valve portion7 closes, the supply of refrigerant into the case chamber 3 through theintroducing-side communication passage 6 is stopped, but refrigerant canbe supplied into the case chamber 3 due to leakage from the clearancebetween the piston and the cylinder.

The degree of opening for communication of the low pressure valveportion 9 is also varied in accordance with the position of the movableportion 10 a, but the manner of variation of the degree of opening forcommunication differs depending upon the position of the movable portion10 a. That is, when the movable portion 10 a is located at the furthestposition of the leading end side direction, the poppet 15 as the lowpressure-side valve body 9 a abuts against the bottom surface 12 n asthe sitting surface and the low pressure valve portion 9 is closed.

If the position of the movable portion 10 a is varied to the base endside, the poppet 15 separates from the bottom surface 12 n. While thepoppet 15 is not separated from the bottom surface 12 n so much, thedegree of opening for communication is varied linearly (region 1).Thereafter, even if the distance between the poppet 15 and the bottomsurface 12 n is increased, if the projection 15 b is still inserted intothe through hole 12 a, the clearance between the projection 15 b and thethrough hole 12 a occupies the most of the degree of opening forcommunication of the low pressure valve portion 9, and this degree ofopening for communication is equivalent to a fixed orifice. Therefore,in this section, the degree of opening for communication is variedsubstantially constantly (region 2). Thereafter, if the projection 15 bis pulled out from the through hole 12 a, the degree of opening forcommunication of the low pressure valve portion 9 is linearly increasedin accordance with the distance between the poppet 15 and the bottomsurface 12 n (region 3). In this region 3, the poppet 15, i.e., the lowpressure-side valve body 9 a separates from the poppet 13 a, i.e., thespool 13 having the high pressure-side valve body 7 a (gap G).Therefore, the high pressure valve portion 7 is closed and the movementof the high pressure-side valve body 7 a toward the base end side islimited, but irrespective of this, the degree of opening forcommunication of the low pressure valve portion 9 can swiftly be larger.

According to the present embodiment, as described above, the dischargepressure Pd acting to the poppet 13 a as the high pressure-side valvebody 7 a acts on both the base end side and the leading end side of thespool 13 in the X direction and the discharge pressure Pd is weakened.Therefore, unlike the conventional technique, it is possible to avoid acase where when the high pressure valve portion is opened, the highpressure valve portion is closed by the discharge flow path sidepressure Pd acting on the high pressure-side valve body and a pressurein the case chamber is reduced. Thus, it is possible to avoid a casewhere in a state in which the angle of the swash plate 2 a of thevariable displacement compressor 2 is small, the degree of opening forcommunication of the high pressure valve portion 7 is reduced or closed,a pressure in the case chamber 3 is reduced and the angle of the swashplate 2 a is increased.

That is, according to the present embodiment, it is possible to keep theangle of the swash plate 2 a small and to reliably obtain a state wherethere is almost no discharge capacity. Therefore, this is suitablyapplied to a variable displacement compressor for a so-calledclutch-less system. In this case, as compared with a system which stopsrotation of a compressor using a clutch, there is a merit that thenumber of parts is reduced, the apparatus configuration can besimplified and its weight can be reduced.

According to the present embodiment, when the poppet 15 as the lowpressure-side valve body 9 a is positioned on the side of the base endby the solenoid 10 as the position control unit, the poppet 13 a as thehigh pressure-side valve body 7 a and the poppet 15 as the lowpressure-side valve body 9 a are separated from each other. Therefore,the degree of opening for communication of the low pressure valveportion 9 can be widened and the poppet 15 is not subjected to anyconstraints by the poppet 13 a. Therefore, when the variabledisplacement compressor 2 is started, the degree of opening forcommunication of the low pressure valve portion 9 can be larger moreswiftly, the control pressure Pc in the case chamber 3 can be reduced,the angle of the swash plate 2 a can be increased, and a necessarydischarge capacity can be secured more swiftly.

Further, since the high pressure-side valve body 7 a and the lowpressure-side valve body 9 a can be separated from each other, even if adischarge pressure Pd acts on the high pressure-side valve body 7 atoward the leading end side in the X direction, the movement of the lowpressure-side valve body 9 a toward the base end side in the X directionis not hindered.

According to the present embodiment, the low pressure valve portion 9 isfully closed when the poppet 13 a as the high pressure-side valve body 7a and the poppet 15 as the low pressure-side valve body 9 a arepositioned on the side of the leading end by the solenoid 10 as theposition control unit. Therefore, it becomes easy to keep the controlpressure Pc in the case chamber 3 high, the leaking flow in the lowpressure valve portion 9 can be reduced and the energy loss can bereduced correspondingly.

Since the low pressure valve portion 9 is configured such that itcloses, the degree of opening for communication when the low pressurevalve portion 9 is closed is naturally small as compared with a casewhere the low pressure valve portion 9 is configured such that it doesnot close. However, according to the present embodiment, since the highpressure-side valve body 7 a and the low pressure-side valve body 9 acan be separated from each other, the degree of opening forcommunication of the low pressure valve portion 9 can be larger moreswiftly as compared with a case where the high pressure-side valve body7 a and the low pressure-side valve body 9 a are integrally formed asone piece, and a state where the low pressure valve portion 9 is closed,i.e., a state where the control pressure Pc in the case chamber 3 ishigh can be switched, more swiftly, to a state where the low pressurevalve portion 9 is opened, i.e., a state where the control pressure Pcin the case chamber 3 is low, and the control response can be enhanced.

Furthermore, according to the present embodiment, the poppet 13 a andthe poppet 15 can be separated more swiftly by the coil spring 17 whichdoes not urge the poppet 13 a and which urges only the poppet 15 towardthe base end side. Therefore, the degree of opening for communication ofthe low pressure valve portion 9 can be larger more swiftly, and thecontrol response can be enhanced.

While a preferred embodiment of the present invention has been describedabove, the invention is not limited to the embodiment and can bevariously modified. For example, the poppet valve can be changed to aball valve or a needle valve. The direction of the suction force causeby the solenoid, the configuration to generate the suction force, theconfiguration of the valve portion, the configuration of the urging unitand the like are not limited to those of the embodiment.

INDUSTRIAL APPLICABILITY

The present invention can be utilized as a control valve for a variabledisplacement compressor.

1. A control valve for a variable displacement compressor comprising ahigh pressure valve portion provided in an introducing-sidecommunication passage which brings a discharge flow path and a controlpressure chamber of the variable displacement compressor intocommunication with each other, and a low pressure valve portion providedin a discharging-side communication passage which brings an intake flowpath and the control pressure chamber into communication with eachother, in which degree of opening for communication of the high pressurevalve portion and the low pressure valve portion are variablycontrolled, thereby varying a pressure in the control pressure chamberto change an angle of a swash plate, wherein the control valve furthercomprises a position control unit which controls advancing/retractingpositions of a high pressure-side valve body of the high pressure valveportion and a low pressure-side valve body of the low pressure valveportion, as a position of the high pressure-side valve body positionedby the position control unit is closer to one side, a degree of openingfor communication of the high pressure valve portion is more widened, apressure on the side of a discharge flow path acting on the highpressure-side valve body is weakened, as a position of the lowpressure-side valve body positioned by the position control unit iscloser to the other side, a degree of opening for communication of thelow pressure valve portion is more widened, and when the highpressure-side valve body and the low pressure-side valve body areintegrally positioned on the one side by the position control unit andthe low pressure-side valve body is positioned on the other side by theposition control unit, the high pressure-side valve body and the lowpressure-side valve body are separated from each other.
 2. The controlvalve for a variable displacement compressor according to claim 1,wherein when the high pressure-side valve body and the low pressure-sidevalve body are positioned on the one side by the position control unit,the low pressure valve portion is fully closed.
 3. The control valve fora variable displacement compressor according to claim 1, furthercomprising an urging unit which urges, of the high pressure-side valvebody and the low pressure-side valve body, only the low pressure-sidevalve body toward the other side.